Compressor with a discharge valve

ABSTRACT

A compressor includes a discharge valve with a first valve head and a second valve head. The first valve head defines a passage that extends through the first valve head along an axial direction. A first spring is coupled to the first valve head. A second valve head is positioned at the passage of the first valve head. A second spring urges the second valve head towards the first valve head.

FIELD OF THE INVENTION

The present subject matter relates generally to compressors and discharge valves for compressors.

BACKGROUND OF THE INVENTION

Certain refrigerator appliances include sealed systems for cooling chilled chambers of the refrigerator appliance. The sealed systems generally include a compressor that generates compressed refrigerant during operation of the sealed system. The compressed refrigerant flows to an evaporator where heat exchange between the chilled chambers and the refrigerant cools the chilled chambers and food items located therein.

Recently, certain refrigerator appliances have included linear compressors for compressing refrigerant. Linear compressors generally include a piston and a driving coil. The driving coil receives a current that generates a force for sliding the piston forward and backward within a chamber. During motion of the piston within the chamber, the piston compresses refrigerant. A discharge valve regulates a flow of pressured refrigerant from the chamber.

Over-pressurization of the chamber can negatively affect performance of the linear compressor, and the discharge valve design frequently exacerbates the over-pressurization. In particular, a mass of the discharge valve can require a cylinder pressure to exceed a discharge muffler pressure by a certain margin before the discharge valve opens. A high mass discharge valve responds slowly and increases the amount of work required to open the discharge valve. However, high mass is generally required to provide a discharge valve that covers the chamber at an end of the cylinder and thereby allow the piston to run and “crash” into the discharge valve without damaging the linear compressor. Thus, a full cylinder diameter discharge valve is disadvantageously massive but has other benefits.

Accordingly, a linear compressor with a discharge valve having features limits over-pressurization of a chamber while also permitting crashing of a piston would be useful.

BRIEF DESCRIPTION OF THE INVENTION

The present subject matter provides a compressor. The compressor includes a discharge valve with a first valve head and a second valve head. The first valve head defines a passage that extends through the first valve head along an axial direction. A first spring urges the first valve head towards a casing. A second valve head is positioned at the passage of the first valve head. A second spring urges the second valve head towards the first valve head. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In a first exemplary embodiment, a compressor is provided. The compressor includes a casing that defines a chamber. A piston is disposed within the chamber of the casing. The piston is reciprocable within the chamber of the casing along an axial direction. A discharge valve includes a housing. A first valve head is positioned adjacent the chamber of the casing. The first valve head has a width along a radial direction that is perpendicular to the axial direction. The first valve head also defines a passage that extends through the first valve head along the axial direction. A first spring is coupled to the housing and the first valve head such that the first spring urges the first valve head towards the casing. A second valve head is positioned at the passage of the first valve head. The second valve head has a width along the radial direction. The width of the second valve head is less than the width of the first valve head. A second spring is coupled to the second valve head such that the second spring urges the second valve head towards the first valve head.

In a second exemplary embodiment, a compressor is provided. The compressor includes a casing that defines a chamber. A piston is disposed within the chamber of the casing. The piston is reciprocable within the chamber of the casing along an axial direction. A discharge valve includes a housing. A first valve head is positioned adjacent the chamber of the casing. The first valve head has a mass. The first valve head also defines a passage that extends through the first valve head along the axial direction. A first spring is coupled to the housing and the first valve head such that the first spring urges the first valve head towards the casing. The first spring has a stiffness. A second valve head is positioned at the passage of the first valve head. The second valve head has a mass. The mass of the second valve head is less than the mass of the first valve head. A second spring is coupled to the second valve head such that the second spring urges the second valve head towards the first valve head. The second spring has a stiffness. The stiffness of the second spring is less than the stiffness of the first spring.

In a third exemplary embodiment, a compressor is provided. The compressor includes a casing that defines a chamber. A piston is disposed within the chamber of the casing. The piston is reciprocable within the chamber of the casing along an axial direction. A discharge valve includes a housing. A valve head is positioned adjacent the chamber of the casing. The valve head defines a passage that extends through the valve head along the axial direction. A spring is coupled to the housing and the valve head such that the spring urges the valve head towards the casing. A reed is positioned at the passage of the valve head. The reed is mounted to the valve head such that the reed is cantilevered over the passage of the valve head.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 is a front elevation view of a refrigerator appliance according to an exemplary embodiment of the present subject matter.

FIG. 2 is schematic view of certain components of the exemplary refrigerator appliance of FIG. 1.

FIG. 3 provides a section view of a linear compressor according to an exemplary embodiment of the present subject matter.

FIG. 4 provides a partial, section view of a discharge valve on a linear compressor according to an exemplary embodiment of the present subject matter.

FIG. 5 provides a section view of a discharge valve according to an exemplary embodiment of the present subject matter.

FIG. 6 provides a section view of a discharge valve according to another exemplary embodiment of the present subject matter.

FIG. 7 provides a perspective view of components of a discharge valve according to an additional exemplary embodiment of the present subject matter.

FIG. 8 provides a section view of the components of the discharge valve of FIG. 7.

FIG. 8 provides an exploded view of the components of the discharge valve of FIG. 7.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 depicts a refrigerator appliance 10 that incorporates a sealed refrigeration system 60 (FIG. 2). It should be appreciated that the term “refrigerator appliance” is used in a generic sense herein to encompass any manner of refrigeration appliance, such as a freezer, refrigerator/freezer combination, and any style or model of conventional refrigerator. In addition, it should be understood that the present subject matter is not limited to use in appliances. Thus, the present subject matter may be used for any other suitable purpose, such as vapor compression within air conditioning units or air compression within air compressors.

In the illustrated exemplary embodiment shown in FIG. 1, the refrigerator appliance 10 is depicted as an upright refrigerator having a cabinet or casing 12 that defines a number of internal chilled storage compartments. In particular, refrigerator appliance 10 includes upper fresh-food compartments 14 having doors 16 and lower freezer compartment 18 having upper drawer 20 and lower drawer 22. The drawers 20 and 22 are “pull-out” drawers in that they can be manually moved into and out of the freezer compartment 18 on suitable slide mechanisms.

FIG. 2 is a schematic view of certain components of refrigerator appliance 10, including a sealed refrigeration system 60 of refrigerator appliance 10. A machinery compartment 62 contains components for executing a known vapor compression cycle for cooling air. The components include a compressor 64, a condenser 66, an expansion device 68, and an evaporator 70 connected in series and charged with a refrigerant. As will be understood by those skilled in the art, refrigeration system 60 may include additional components, e.g., at least one additional evaporator, compressor, expansion device, and/or condenser. As an example, refrigeration system 60 may include two evaporators.

Within refrigeration system 60, refrigerant flows into compressor 64, which operates to increase the pressure of the refrigerant. This compression of the refrigerant raises its temperature, which is lowered by passing the refrigerant through condenser 66. Within condenser 66, heat exchange with ambient air takes place so as to cool the refrigerant. A fan 72 is used to pull air across condenser 66, as illustrated by arrows A_(C), so as to provide forced convection for a more rapid and efficient heat exchange between the refrigerant within condenser 66 and the ambient air. Thus, as will be understood by those skilled in the art, increasing air flow across condenser 66 can, e.g., increase the efficiency of condenser 66 by improving cooling of the refrigerant contained therein.

An expansion device (e.g., a valve, capillary tube, or other restriction device) 68 receives refrigerant from condenser 66. From expansion device 68, the refrigerant enters evaporator 70. Upon exiting expansion device 68 and entering evaporator 70, the refrigerant drops in pressure. Due to the pressure drop and/or phase change of the refrigerant, evaporator 70 is cool relative to compartments 14 and 18 of refrigerator appliance 10. As such, cooled air is produced and refrigerates compartments 14 and 18 of refrigerator appliance 10. Thus, evaporator 70 is a type of heat exchanger which transfers heat from air passing over evaporator 70 to refrigerant flowing through evaporator 70.

Collectively, the vapor compression cycle components in a refrigeration circuit, associated fans, and associated compartments are sometimes referred to as a sealed refrigeration system operable to force cold air through compartments 14, 18 (FIG. 1). The refrigeration system 60 depicted in FIG. 2 is provided by way of example only. Thus, it is within the scope of the present subject matter for other configurations of the refrigeration system to be used as well.

FIG. 3 provides a section view of a linear compressor 100 according to an exemplary embodiment of the present subject matter. As discussed in greater detail below, linear compressor 100 is operable to increase a pressure of fluid within a chamber 112 of linear compressor 100. Linear compressor 100 may be used to compress any suitable fluid, such as refrigerant or air. In particular, linear compressor 100 may be used in a refrigerator appliance, such as refrigerator appliance 10 (FIG. 1) in which linear compressor 100 may be used as compressor 64 (FIG. 2). As may be seen in FIG. 3, linear compressor 100 defines an axial direction A, a radial direction R and a circumferential direction C. Linear compressor 100 may be enclosed within a hermetic or air-tight shell (not shown). The hermetic shell can, e.g., hinder or prevent refrigerant from leaking or escaping from refrigeration system 60.

Turning now to FIG. 3, linear compressor 100 includes a casing 110 that extends between a first end portion 102 and a second end portion 104, e.g., along the axial direction A. Casing 110 includes various static or non-moving structural components of linear compressor 100. In particular, casing 110 includes a cylinder assembly 111 that defines a chamber 112. Cylinder assembly 111 is positioned at or adjacent second end portion 104 of casing 110. Chamber 112 extends longitudinally along the axial direction A. Casing 110 also includes a motor mount mid-section 113 and an end cap 115 positioned opposite each other about a motor. A stator, e.g., including an outer back iron 150 and a driving coil 152, of the motor is mounted or secured to casing 110, e.g., such that the stator is sandwiched between motor mount mid-section 113 and end cap 115 of casing 110. Linear compressor 100 also includes valves (such as a discharge valve assembly 117 at an end of chamber 112) that permit refrigerant to enter and exit chamber 112 during operation of linear compressor 100.

A piston assembly 114 with a piston head 116 is slidably received within chamber 112 of cylinder assembly 111. In particular, piston assembly 114 is slidable along the axial direction A. During sliding of piston head 116 within chamber 112, piston head 116 compresses refrigerant within chamber 112. As an example, from a top dead center position, piston head 116 can slide within chamber 112 towards a bottom dead center position along the axial direction A, i.e., an expansion stroke of piston head 116. When piston head 116 reaches the bottom dead center position, piston head 116 changes directions and slides in chamber 112 back towards the top dead center position, i.e., a compression stroke of piston head 116. It should be understood that linear compressor 100 may include an additional piston head and/or additional chamber at an opposite end of linear compressor 100. Thus, linear compressor 100 may have multiple piston heads in alternative exemplary embodiments.

As may be seen in FIG. 3, linear compressor 100 also includes an inner back iron assembly 130. Inner back iron assembly 130 is positioned in the stator of the motor. In particular, outer back iron 150 and/or driving coil 152 may extend about inner back iron assembly 130, e.g., along the circumferential direction C. Inner back iron assembly 130 also has an outer surface 137. At least one driving magnet 140 is mounted to inner back iron assembly 130, e.g., at outer surface 137 of inner back iron assembly 130. Driving magnet 140 may face and/or be exposed to driving coil 152. In particular, driving magnet 140 may be spaced apart from driving coil 152, e.g., along the radial direction R by an air gap. Thus, the air gap may be defined between opposing surfaces of driving magnet 140 and driving coil 152. Driving magnet 140 may also be mounted or fixed to inner back iron assembly 130 such that an outer surface of driving magnet 140 is substantially flush with outer surface 137 of inner back iron assembly 130. Thus, driving magnet 140 may be inset within inner back iron assembly 130. In such a manner, the magnetic field from driving coil 152 may have to pass through only a single air gap between outer back iron 150 and inner back iron assembly 130 during operation of linear compressor 100, and linear compressor 100 may be more efficient relative to linear compressors with air gaps on both sides of a driving magnet.

As may be seen in FIG. 3, driving coil 152 extends about inner back iron assembly 130, e.g., along the circumferential direction C. Driving coil 152 is operable to move the inner back iron assembly 130 along the axial direction A during operation of driving coil 152. As an example, a current may be induced within driving coil 152 by a current source (not shown) to generate a magnetic field that engages driving magnet 140 and urges piston assembly 114 to move along the axial direction A in order to compress refrigerant within chamber 112 as described above and will be understood by those skilled in the art. In particular, the magnetic field of driving coil 152 may engage driving magnet 140 in order to move inner back iron assembly 130 and piston head 116 along the axial direction A during operation of driving coil 152. Thus, driving coil 152 may slide piston assembly 114 between the top dead center position and the bottom dead center position, e.g., by moving inner back iron assembly 130 along the axial direction A, during operation of driving coil 152.

Linear compressor 100 may include various components for permitting and/or regulating operation of linear compressor 100. In particular, linear compressor 100 includes a controller (not shown) that is configured for regulating operation of linear compressor 100. The controller is in, e.g., operative, communication with the motor, e.g., driving coil 152 of the motor. Thus, the controller may selectively activate driving coil 152, e.g., by inducing current in driving coil 152, in order to compress refrigerant with piston assembly 114 as described above.

The controller includes memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of linear compressor 100. The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory can be a separate component from the processor or can be included onboard within the processor. Alternatively, the controller may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

Linear compressor 100 also includes a spring 120. Spring 120 is positioned in inner back iron assembly 130. In particular, inner back iron assembly 130 may extend about spring 120, e.g., along the circumferential direction C. Spring 120 also extends between first and second end portions 102 and 104 of casing 110, e.g., along the axial direction A. Spring 120 assists with coupling inner back iron assembly 130 to casing 110, e.g., cylinder assembly 111 of casing 110. In particular, inner back iron assembly 130 is fixed to spring 120 at a middle portion of spring 120 as discussed in greater detail below.

During operation of driving coil 152, spring 120 supports inner back iron assembly 130. In particular, inner back iron assembly 130 is suspended by spring 120 within the stator or the motor of linear compressor 100 such that motion of inner back iron assembly 130 along the radial direction R is hindered or limited while motion along the axial direction A is relatively unimpeded. Thus, spring 120 may be substantially stiffer along the radial direction R than along the axial direction A. In such a manner, spring 120 can assist with maintaining a uniformity of the air gap between driving magnet 140 and driving coil 152, e.g., along the radial direction R, during operation of the motor and movement of inner back iron assembly 130 on the axial direction A. Spring 120 can also assist with hindering side pull forces of the motor from transmitting to piston assembly 114 and being reacted in cylinder assembly 111 as a friction loss.

Inner back iron assembly 130 includes an outer cylinder 136 and a sleeve 139. Outer cylinder 136 defines outer surface 137 of inner back iron assembly 130 and also has an inner surface 138 positioned opposite outer surface 137 of outer cylinder 136. Sleeve 139 is positioned on or at inner surface 138 of outer cylinder 136. A first interference fit between outer cylinder 136 and sleeve 139 may couple or secure outer cylinder 136 and sleeve 139 together. In alternative exemplary embodiments, sleeve 139 may be welded, glued, fastened, or connected via any other suitable mechanism or method to outer cylinder 136.

Sleeve 139 extends about spring 120, e.g., along the circumferential direction C. In addition, a middle portion of spring 120 is mounted or fixed to inner back iron assembly 130 with sleeve 139. Sleeve 139 extends between inner surface 138 of outer cylinder 136 and the middle portion of spring 120, e.g., along the radial direction R. A second interference fit between sleeve 139 and the middle portion of spring 120 may couple or secure sleeve 139 and the middle portion of spring 120 together. In alternative exemplary embodiments, sleeve 139 may be welded, glued, fastened, or connected via any other suitable mechanism or method to the middle portion of spring 120.

Outer cylinder 136 may be constructed of or with any suitable material. For example, outer cylinder 136 may be constructed of or with a plurality of (e.g., ferromagnetic) laminations. The laminations are distributed along the circumferential direction C in order to form outer cylinder 136 and are mounted to one another or secured together, e.g., with rings pressed onto ends of the laminations. Outer cylinder 136 defines a recess that extends inwardly from outer surface 137 of outer cylinder 136, e.g., along the radial direction R. Driving magnet 140 is positioned in the recess on outer cylinder 136, e.g., such that driving magnet 140 is inset within outer cylinder 136.

A piston flex mount 160 is mounted to and extends through inner back iron assembly 130. In particular, piston flex mount 160 is mounted to inner back iron assembly 130 via sleeve 139 and spring 120. Thus, piston flex mount 160 may be coupled (e.g., threaded) to spring 120 at the middle portion of spring 120 in order to mount or fix piston flex mount 160 to inner back iron assembly 130. A coupling 170 extends between piston flex mount 160 and piston assembly 114, e.g., along the axial direction A. Thus, coupling 170 connects inner back iron assembly 130 and piston assembly 114 such that motion of inner back iron assembly 130, e.g., along the axial direction A, is transferred to piston assembly 114. Coupling 170 may extend through driving coil 152, e.g., along the axial direction A.

Coupling 170 may be a compliant coupling that is compliant or flexible along the radial direction R. In particular, coupling 170 may be sufficiently compliant along the radial direction R such that little or no motion of inner back iron assembly 130 along the radial direction R is transferred to piston assembly 114 by coupling 170. In such a manner, side pull forces of the motor are decoupled from piston assembly 114 and/or cylinder assembly 111 and friction between piston assembly 114 and cylinder assembly 111 may be reduced.

Piston flex mount 160 defines at least one suction gas inlet 162. Suction gas inlet 162 of piston flex mount 160 extends, e.g., along the axial direction A, through piston flex mount 160. Thus, a flow of fluid, such as air or refrigerant, may pass through piston flex mount 160 via suction gas inlet 162 of piston flex mount 160 during operation of linear compressor 100.

Piston head 116 also defines at least one opening 118. Opening 118 of piston head 116 extends, e.g., along the axial direction A, through piston head 116. Thus, the flow of fluid may pass through piston head 116 via opening 118 of piston head 116 into chamber 112 during operation of linear compressor 100. In such a manner, the flow of fluid (that is compressed by piston head 116 within chamber 112) may flow through piston flex mount 160 and inner back iron assembly 130 to piston assembly 114 during operation of linear compressor 100.

FIG. 4 provides a partial, section view of a discharge valve 200 according to an exemplary embodiment of the present subject matter. Discharge valve 200 is described in greater detail below in the context of linear compressor 100. Thus, discharge valve 200 may be used as discharge valve assembly 117. However, it should be understood that discharge valve 200 may be used in or with any suitable compressor in alternative exemplary embodiments, e.g., to regulate pressurized fluid flow from a chamber. As discussed in greater detail below, discharge valve 200 includes features for limiting over-pressurization of chamber 112 and thereby increasing an efficiency of linear compressor 100, e.g., by requiring less work to open discharge valve 200 relative to other discharge valves. As may be seen in FIG. 4, discharge valve 200 includes a housing 210, a first valve head 220, a first spring 230, a second valve head 240 and a second spring 250.

Housing 210 may include an end wall 212 and a cylindrical side wall 214. Cylindrical side wall 214 is mounted to end wall 212, and cylindrical side wall 214 extends from end wall 212, e.g., along the axial direction A, to cylinder assembly 111 of casing 110. Housing 210 may be mounted or fixed to casing 110, and other components of discharge valve 200 may be disposed within housing 210. For example, a plate 218 of housing 210 at a distal end of cylindrical side wall 214 may be positioned at or on cylinder assembly 111, and a seal 219 may extend between cylinder assembly 111 and plate 218 of housing 210, e.g., along the axial direction A, in order to limit fluid leakage at an axial gap between casing 110 and housing 210. Fasteners (not shown) may extend through plate 218 into casing 110 to mount housing 210 to casing 110. First valve head 220, first spring 230, second valve head 240 and/or second spring 250 may be disposed within housing 210 when housing 210 is mounted to casing 110.

First valve head 220 is positioned at or adjacent chamber 112 of cylinder assembly 111. First valve head 220 defines a passage 222 that extends through first valve head 220, e.g., along the axial direction A. Passage 222 may be contiguous with chamber 112. First spring 230 is coupled to housing 210 and first valve head 220, and first spring 230 is configured to urge first valve head 220 towards or against cylinder assembly 111, e.g., along the axial direction A. As shown in FIG. 4, one end of first spring 230 may be mounted to end wall 212 of housing 210 at a bracket 216 of end wall 212, and another end of first spring 230 may be mounted to an outer diameter of a support 224 of first valve head 220. Thus, first spring 230 may be compressed between end wall 212 (e.g., bracket 216 of end wall 212) and first valve head 220 within housing 210. First spring 230 may be a coil or helical spring in certain exemplary embodiments.

Second valve head 240 is positioned at passage 222 of first valve head 220, e.g., on first valve head 220. Second spring 250 is coupled to second valve head 240, and second spring 250 is configured for urging second valve head 240 towards or against first valve head 220. As shown in FIG. 4, discharge valve 200 may include a retainer 260 with a post 262. Retainer 260 is mounted to first valve head 220. For example, retainer 260 may be snap-fit, press-fit, ultra-sonically welded, fastened, adhered or otherwise suitable mounted to support 224 of first valve head 220 at an inner diameter of support 224. Post 262 is positioned at a central portion of retainer 260 and extends, e.g., along the axial direction A, towards second valve head 240. Second spring 250 may be compressed between post 262 and second valve head 240. Second spring 250 may be a coil or helical spring in certain exemplary embodiments.

First valve head 220 and second valve head 240 are each adjustable between an open position (not shown) and a closed position (FIG. 4). Thus, first valve head 220 and second valve head 240 may be moveable, e.g., along the axial direction A, relative to casing 110. In particular, during operation of linear compressor, piston assembly 114 reciprocates within chamber 112 and pressurizes fluid, and first and second valve heads 220, 240 shift between the open and closed positions. For example, first and second springs 230, 250 bias first and second valve heads 220, 240 towards the closed position, respectively. Thus, first and second valve heads 220, 240 are normally closed. When first valve head 220 is in the closed position, first valve head 220 may be seated against cylinder assembly 111 and thus assist with sealing chamber 112. Similarly, second valve head 240 may be seated against first valve head 220, e.g., opposite chamber 112, when second valve head 240 is in the closed position. Thus, when first and second valve heads 220, 240 are both closed, discharge valve 200 may seal chamber 112 and thereby assist with pressurization of fluid due to motion of piston assembly 114 within chamber 112.

When the fluid in chamber 112 reaches a first threshold pressure, second valve head 240 may open. For example, fluid within chamber 112 may apply a force onto second valve head 240 that overcomes the force applied to second valve head 240 by second spring 250 such that second valve head 240 moves, e.g., along the axial direction A, away from first valve head 220 to the open position. When second valve head 240 is in the open position, fluid from chamber 112 may flow through passage 222 out of chamber 112 and into housing 210.

First valve head 220 may open when the fluid in chamber 112 reaches a second threshold pressure, e.g., that is greater than the first threshold pressure. For example, fluid within chamber 112 may apply a force onto first valve head 220 that overcomes the force applied to first valve head 220 by first spring 230 such that first valve head 220 moves, e.g., along the axial direction A, away from cylinder assembly 111 to the open position. When first valve head 220 is in the open position, fluid from chamber 112 may flow through out of chamber 112 through an axial gap between first valve head 220 and cylinder assembly 111 into housing 210.

First valve head 220 may also move from the closed position to the open position when piston assembly 114 strikes or impacts first valve head 220. Thus, second valve head 240 may correspond to a flow path for pressurized fluid from chamber 112 during normal operation of linear compressor 100, and first valve head 220 may correspond to a movable end wall of cylinder assembly 111 that seals chamber 112 during normal operation of linear compressor 100 but is movable, e.g., along the axial direction A, to limit damage to piston assembly 114 when piston assembly 114 strikes or impacts first valve head 220.

As may be seen from the above, discharge valve 200 may have a valve-on-valve design that includes at least two mechanisms for releasing pressurized fluid from chamber 112. In particular, second valve head 240 may be piggybacked onto first valve head 220. First valve head 220 may be larger and less responsive while second valve head 240 is smaller and more responsive. For example, second valve head 240 may react and open under normal operating conditions and thereby improve compressor efficiency relative to utilizing only first valve head 220.

Various parameters of first valve head 220 and second valve head 240 may be varied to allow second valve head 240 to be smaller and more responsive relative to first valve head 220. For example, a mass of first valve head 220 may be greater than a mass of second valve head 240. As a particular example, the mass of first valve head 220 may be no less than twice the mass of second valve head 240. First valve head 220 may also have a width W1, e.g., along the radial direction R, and second valve head 240 may have a width W2, e.g., along the radial direction R. The width W2 of second valve head 240 may be less than the width W1 of first valve head 220. As a particular example, the width W1 of first valve head 220 may be no less than twice the width W2 of second valve head 240. First and second valve heads 220, 240 may have circular outer perimeters, and the widths W1, W2 of first and second valve heads 220, 240 may be diameters. Parameters of first spring 230 and second spring 250 may also be varied to allow second valve head 240 to be more responsive relative to first valve head 220. For example, a stiffness of first spring 230 may be greater than a stiffness of second spring 250. As a particular example, the stiffness of first spring 230 may be no less than twice the stiffness of second spring 250. Such relative sizing of first and second valve heads 220, 240 and/or first and second springs 230, 250 assists with providing the efficiency increase in linear compressor 100 noted above.

As may be seen in FIG. 4, first spring 230 may assist with seating first valve head 220 on casing 110 at chamber 112. In particular, first valve head 220 may extend radially over chamber 112. Thus, the width W1 of first valve head 220 may be greater than a width of chamber 112, e.g., along the radial direction R. Such sizing of first valve head 220 relative to chamber 112 provides that first valve head 220 may be wider than piston assembly 114, e.g., along the radial direction R. Thus, first valve head 220 may be sized to seal chamber 112 while also allowing crashing of piston assembly 114 against first valve head 220 rather than other fixed components of cylinder assembly 111.

Second spring 250 may assist with seating second valve head 240 on first valve head 220 at passage 222. In particular, second valve head 240 may extend radially over passage 222. Thus, the width W2 of second valve head 240 may be greater than a width of passage 222, e.g., along the radial direction R.

FIG. 5 provides a section view of a discharge valve 300 according to an exemplary embodiment of the present subject matter. Discharge valve 300 is constructed in a similar manner to discharge valve 200 (FIG. 4) and includes numerous common components, as shown with common reference numerals. However, first and second springs 230, 250 are mounted in a different manner in discharge valve 300.

As shown in FIG. 5, first spring 230 is coupled to housing 210 and first valve head 220. In particular, one end of first spring 230 may be mounted to end wall 212 of housing 210 at a bracket 216 of end wall 212, and another end of first spring 230 may be received within a retainer 310 mounted on first valve head 220. Thus, first spring 230 may extend between end wall 212 (e.g., bracket 216 of end wall 212) and retainer 310 within housing 210. Retainer 310 may be snap-fit, press-fit, ultra-sonically welded, fastened, adhered or otherwise suitable mounted to support 224 of first valve head 220 at an outer diameter of support 224. Retainer 310 includes a post 312. Post 312 is positioned at a central portion of retainer 310 and extends, e.g., along the axial direction A, towards second valve head 240. Second spring 250 may extend between post 312 and second valve head 240.

FIG. 6 provides a section view of a discharge valve 400 according to another exemplary embodiment of the present subject matter. Discharge valve 400 is constructed in a similar manner to discharge valve 200 (FIG. 4) and includes numerous common components, as shown with common reference numerals. However, second spring 250 is mounted in a different manner in discharge valve 400.

As shown in FIG. 6, discharge valve 400 includes a post 410. Post 410 is mounted to end wall 212 of housing 210. For example, post 410 may be mounted to or formed with bracket 216 of end wall 212. Post 410 extends, e.g., along the axial direction A, from end wall 212 towards second valve head 240. Second spring 250 extends between post 410 and second valve head 240 within housing 210.

FIG. 7 provides a perspective view of components of a discharge valve 500 according to an additional exemplary embodiment of the present subject matter. FIG. 8 provides a second view of the components of discharge valve 500. FIG. 9 provides an exploded view of the components of discharge valve 500. Discharge valve 500 may be used in or with any suitable compressor, such as linear compressor 100. As an example, the components of discharge valve 500 may be used with linear compressor 100 in a similar manner to that shown in FIG. 4 for discharge valve 200.

As may be seen in FIG. 7, discharge valve 500 includes a valve head 510. Valve head 510 may be used and positioned in the same or similar manner to that shown in FIG. 4 for first valve head 220. Thus, valve head 510 may be coupled to first spring 230 and positioned at or adjacent chamber 112. Valve head 510 defines a passage 512 that extends through valve head 510, e.g., along the axial direction A.

A reed 520 is positioned at passage 512 of valve head 510. Reed 520 may be mounted to valve head 510 such that reed 520 is cantilevered over passage 512 of valve head 510. Reed 520 may adjust between an open position (not shown) and a closed position (FIG. 8). A distal end of reed 520 is seated on valve head 510 when reed 520 is closed. Conversely, the distal end of reed 520 is spaced apart from valve head 510 when reed 520 is open. Thus, reed 520 limits or blocks fluid flow through passage 512 when reed 520 is in the closed position while reed 520 permits fluid flow through passage 512 when reed 520 is in the open position.

A reed damper or additional reed 525 may be disposed on or over reed valve 520. Thus, reed valve 520 may be positioned between passage 512 and additional reed 525. Additional reed 525 may be stiffer than reed valve 520, e.g., along the axial direction A, in certain exemplary embodiments. Additional reed 525 may dampen opening or deformation of reed 520. For example, additional reed 525 may limit or prevent reed 520 from impacting a valve stop 528 as reed 520 shifts open. Valve stop 528 restricts movement of reed 520 and additional reed 525 during the discharge process, e.g., thereby preventing excess stress in reed 520 and additional reed 525. Thus, valve stop 528 may limit displacement or deformation of reed 520 and/or additional reed 525, e.g., along the axial direction A, away from passage 512. As an example, the distal end of reed 520 and/or additional reed 525 may be positioned against valve stop 528 when reed 520 is open, and the distal end of reed 520 and/or additional reed 525 may be spaced apart from valve stop 528 when reed 520 is closed. Discharge valve 500 may also include a shaft 530 mounted to valve head 510, e.g., above reed 520. Shaft 530 may assist with mounting reed 520, additional reed 525 and/or valve stop 528 to valve head 510.

In a similar manner to that described above for discharge valve 200, discharge valve 500 may have a valve-on-valve design that includes at least two mechanisms for releasing pressurized fluid from chamber 112. In particular, reed 520 may be piggybacked onto valve head 510. Valve head 510 may be larger and less responsive while reed 520 is smaller and more responsive. For example, reed 520 may react and open under normal operating conditions and thereby improve compressor efficiency relative to utilizing only valve head 510. Thus, e.g., a mass of reed 520 may be less than a mass of valve head 510.

Discharge valve 200 (FIG. 4), discharge valve 300 (FIG. 5), discharge valve 400 (FIG. 6) and discharge valve 500 (FIG. 7) may be used in or with any suitable compressor. For example, discharge valve 200, discharge valve 300, discharge valve 400 and discharge valve 500 may be used in or with linear compressor 100, as discharge valve assembly 117. As another example, discharge valve 200, discharge valve 300, discharge valve 400 and discharge valve 500 may be used in or with the linear compressor described in U.S. Patent Publication No. 2015/0226197 of Gregory William Hahn et al., which is hereby incorporated by reference in its entirety for all purposes. Thus, e.g., discharge valve 200, discharge valve 300, discharge valve 400 and discharge valve 500 may be used in or with linear compressors with planar springs rather than a machined spring.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A compressor, comprising: a casing defining a chamber; a piston disposed within the chamber of the casing, the piston reciprocable within the chamber of the casing along an axial direction; a discharge valve comprising a housing; a first valve head positioned adjacent the chamber of the casing, the first valve head having a width along a radial direction that is perpendicular to the axial direction, the first valve head also defining a passage that extends through the first valve head along the axial direction; a first spring coupled to the housing and the first valve head such that the first spring urges the first valve head towards the casing; a second valve head positioned at the passage of the first valve head, the second valve head having a width along the radial direction, the width of the second valve head being less than the width of the first valve head; and a second spring coupled to the second valve head such that the second spring urges the second valve head towards the first valve head.
 2. The compressor of claim 1, wherein the housing comprises an end wall and a cylindrical side wall, the cylindrical side wall extending from the end wall to the casing, the first spring extending between the end wall of the housing and the first valve head within the housing.
 3. The compressor of claim 2, wherein the discharge valve further comprises a post that is mounted to the end wall of the housing, the second spring extending between the post and the second valve head within the housing.
 4. The compressor of claim 2, wherein the discharge valve further comprises a retainer mounted to the first valve head, the second spring extending between the retainer and the second valve head within the housing.
 5. The compressor of claim 1, wherein the first and second valve heads have circular outer perimeters and the widths of the first and second valve heads are diameters.
 6. The compressor of claim 1, wherein the width of the first valve head no less than twice the width of the second valve head.
 7. The compressor of claim 1, wherein the first valve head is seated on the casing when the first valve head is closed and the second valve head is seated on the first valve head when the second valve head is closed.
 8. The compressor of claim 1, wherein the first and second springs are coil springs.
 9. The compressor of claim 1, wherein a stiffness of the first spring is greater than a stiffness of the second spring.
 10. The compressor of claim 1, wherein a mass of the first valve head is greater than a mass of the second valve head.
 11. A compressor, comprising: a casing defining a chamber; a piston disposed within the chamber of the casing, the piston reciprocable within the chamber of the casing along an axial direction; a discharge valve comprising a housing; a first valve head positioned adjacent the chamber of the casing, the first valve head having a mass, the first valve head also defining a passage that extends through the first valve head along the axial direction; a first spring coupled to the housing and the first valve head such that the first spring urges the first valve head towards the casing, the first spring having a stiffness; a second valve head positioned at the passage of the first valve head, the second valve head having a mass, the mass of the second valve head being less than the mass of the first valve head; and a second spring coupled to the second valve head such that the second spring urges the second valve head towards the first valve head, the second spring having a stiffness, the stiffness of the second spring being less than the stiffness of the first spring.
 12. The compressor of claim 11, wherein the housing comprises an end wall and a cylindrical side wall, the cylindrical side wall extending from the end wall to the casing, the first spring extending between the end wall of the housing and the first valve head within the housing.
 13. The compressor of claim 12, wherein the discharge valve further comprises a post that is mounted to the end wall of the housing, the second spring extending between the post and the second valve head within the housing.
 14. The compressor of claim 12, wherein the discharge valve further comprises a retainer mounted to the first valve head, the second spring extending between the retainer and the second valve head within the housing.
 15. The compressor of claim 1, wherein the first valve head is seated on the casing when the first valve head is closed and the second valve head is seated on the first valve head when the second valve head is closed.
 16. The compressor of claim 1, wherein a mass of the first valve head is greater than a mass of the second valve head.
 17. A compressor, comprising: a casing defining a chamber; a piston disposed within the chamber of the casing, the piston reciprocable within the chamber of the casing along an axial direction; a discharge valve comprising a housing; a valve head positioned adjacent the chamber of the casing, the valve head defining a passage that extends through the valve head along the axial direction; a spring coupled to the housing and the valve head such that the spring urges the valve head towards the casing; a reed positioned at the passage of the valve head, the reed mounted to the valve head such that the reed is cantilevered over the passage of the valve head.
 18. The compressor of claim 17, wherein the valve head is seated on the casing when the valve head is closed and the reed is seated on the valve head when the reed is closed.
 19. The compressor of claim 18, wherein the discharge valve further comprises a valve stop and a shaft mounted to the valve head, the reed positioned against the valve stop when the reed is open, the shaft extending across an annular side wall of the valve head, the valve stop positioned between the reed and the shaft.
 20. The compressor of claim 18, wherein the discharge valve further comprises a damper reed mounted to the valve head and positioned on the reed, the damper reed opposing movement of the reed away from the passage of the valve head. 